Facile Generation of Thermally Activated Delayed Fluorescence and Fabrication of Highly Efficient Non‐Doped OLEDs Based on Triazine Derivatives

A series of donor–acceptor–donor triazine‐based molecules with thermally activated delayed fluorescence (TADF) properties were synthesized to obtain highly efficient blue‐emitting OLEDs with non‐doped emitting layers (EMLs). The targeted molecules use a triazine core as the electron acceptor, and a...

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Published in:Chemistry : a European journal 2019-12, Vol.25 (72), p.16699-16711
Main Authors: Chih, Hsin‐Yun, Chen, Ying‐Wei, Hsieh, Yi‐Chun, Li, Wei‐Cheng, Liao, Chia‐Wei, Lin, Chun‐Han, Chiu, Ting‐Ya, Tsai, Wei‐Wen, Lu, Chin‐Wei, Chang, Chih‐Hao
Format: Article
Language:English
Subjects:
Benzene
blue-emitting OLEDs
Charge transfer
Chemistry
donor–acceptor systems
Electroluminescence
Electrons
Emission
Emitters
Emitters (electron)
Energy gap
Energy levels
Fabrication
Fluorescence
Molecular structure
Organic light emitting diodes
Quantum efficiency
Triazine
triazines
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Summary:A series of donor–acceptor–donor triazine‐based molecules with thermally activated delayed fluorescence (TADF) properties were synthesized to obtain highly efficient blue‐emitting OLEDs with non‐doped emitting layers (EMLs). The targeted molecules use a triazine core as the electron acceptor, and a benzene ring as the conjugated linker with different electron donors to alternate the energy level of the HOMO to further tune the emission color. The introduction of long alkyl chains on the triazine core inhibits the unwanted intermolecular D–D/A–A‐type π–π interactions, resulting in the intermolecular D–A charge transfer. The weak aggregation‐caused quenching (ACQ) effect caused by the suppressed intermolecular D–D/A–A‐type π–π interaction further enhances the emission. The crowded molecular structure allows the electron donor and acceptor to be nearly orthogonal, thereby reducing the energy gap between triplet and singlet excited states (ΔEST). As a result, blue‐emitting devices with TH‐2DMAC and TH‐2DPAC non‐doped EMLs showed satisfactory efficiencies of 12.8 % and 15.8 %, respectively, which is one of the highest external quantum efficiency (EQEs) reported for blue TADF emitters (λpeak
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.201904411